Slide valve for material in powder or small-piece form

Abstract: The valve comprises a rigid frame (10) with walls (12) defining a passage mouth (8) for the material and a valving member (9) in the form of a flat horizontal plate; the valving member (9) is movable horizontally through a slot (13) provided in a wall (12a) and is of such a size as to close the passage mouth (8); an elastomeric material gasket means (20) in the form of a closed ring is fixed to the frame (10) and extends along the upper peripheral edge of the passage mouth (8); when viewed in vertical cross-section, the gasket means (20) comprises a lip (21) which projects downwards towards the interior of the mouth (8) and is in contact with the upper surface of the valving member (9) when this is inserted into the passage mouth (8).

Description: This invention relates to a slide valve for material in powder or small-piece form. A typical application of the valve in object is on the lower surface of silos or below a hopper for intercepting the descent of the material. In particular the invention relates to a valve comprising, in combination: a rigid frame with vertical walls defining a passage mouth for the material, having two straight lateral walls parallel one to the other; a flat horizontal plate, defining a valving member to close the passage mouth, horizontally movable through a slot provided in a wall, said plate sliding along said lateral walls, the width of the plate being equal to the distance between the lateral walls; an elastomeric material gasket means in a form of a closed ring fixed to the frame and extending along the upper peripheral edge of the passage mouth, said gasket means comprising, when viewed in section, a lip which projects downward toward the interior of the mouth in contact with the upper surface of the plate, the outer surface of the lip converging downwardly toward the center of the passage mouth, over the upper edge surface of the plate. A technical problem connected with such valves is to prevent the material seeping beyond the valving member when this is in its closure position and to also prevent the material seeping through the passage slot for the valving member when this is at rest and is then pulled rearwards. This problem is exacerbated by the fact that said valves are generally of relatively very large dimensions (the mouth usually has dimensions exceeding 15 cm x 15 cm) and therefore require robust components formed by structural steel working, their parts in addition generally operating in the presence of material which can be very abrasive. FR-A-2640598 discloses a valve of the above type. The peculiar structure of the valve shown in FR-A-2640598 is such that in the region of the passage mouth the valving member, namely the horizontal plate, is not supported by anything but the lower gasket means. So, when the mouth is relatively very large, as in the case the valve is put under big silos, and the powder material is relatively heavy, then the horizontal plate is subjected to a relatively high weight which is opposed only by the gasket means. So the gasket means, being made of an elastomeric material, will be compressed and the horizontal plate will unavoidably sink in the vertical direction, and the powder material will seep out, so the main function of the valve is lacking. An object of the present invention is therefore to solve said technical problem within the framework of an operationally reliable solution which is constructionally simple and economical. The above mentioned object and further objects are attained by the present invention as characterised in the claims, wherein the horizontal plate is supported by idle means which are pivotably fixed to the lateral walls and which act against the lower edge surface of the plate, so that any vertical sinking of the plate relatively to the passage mouth is prevented. The invention is described in detail hereinafter with the aid of the accompanying figures, which illustrate one embodiment thereof. Figure 1 is a perspective view of the valve. Figure 2 is a section on the vertical plane II-II of Figure 1. Figure 3 is a section on the vertical plane III-III of Figure 1. Figure 4 is a plan view of an embodiment of the valve different from the preceding of Figure 1. Figure 5 is a plan view of a further embodiment of the valve different from the preceding. Figure 6 is a section on the plane VI-VI of Figure 5. Figure 7 is a sectional view similar to Figure 2, showing a further embodiment of the invention. The valve shown in Figures 1-3 comprises a rigid frame 10, in particular of metal, comprising four section bars of C cross-section arranged to define a square or rectangle. Each of the section bars 11 comprises a vertical wall 12. The four vertical walls 12 define a prismatic mouth 8 for passage of the material. One of the walls 12, indicated by 12a, possesses a horizontally extending slot 13 through which a valving member 9 in the form of a horizontal flat plate passes with horizontal movement. The valving member 9 is of such a size as to close the passage mouth 8 when viewed in plan. Specifically, the width of the valving member 9 is equal, save for a small clearance, to the distance between the two opposing walls 12 along which it slides, whereas the length of the valving member 9 is greater than the distance between the other two walls 12 so that, even when in its closure position, the valving member 9 projects beyond the mouth 8 through the slot 13. The mouth 8 is closed by pushing the valving member 9 forwards into the mouth 8, opening being achieved vice versa by pulling the valving member 9 rearwards. During said movement, the valving member 9 is guided by idle wheels 6 pivoted to two lateral walls 12 to act against the lower surface of the valving member. For use, the frame 10 is fixed between an upper convergent surface 2 (for example a hopper or the lower surface of a silo) and a lower transit surface 3 for the material. The material hence descends from the top downwards through the mouth 8 (Figures 2 and 3). According to the invention, a gasket means 20 of elastomeric material is fixed to the frame 10 to extend in the form of a closed ring along the upper peripheral edge of the mouth 8. The gasket means 20 consequently comprises four sides extending along the four upper sides of the mouth 8. When viewed in vertical cross-section (Figures 2 and 3), the gasket means 20 comprises a lip 21 which projects downwards towards the interior of the mouth 8. Said lip 21 extends along the four sides of the upper peripheral edge of the mouth 8, with its outer surface converging downwards. The lower surface of said lip 21 is in contact with the upper surface of the valving member 9 when this is inserted into the mouth 8. The gasket means 20 also comprises a horizontal flat rim 22 which is fixed to a corresponding upper horizontal rim 14 of the frame 10, the rim 14 being formed by the upper horizontal flanges of the section bars 11. The lip 21 is joined to the inner edge of the flat rim 22. The gasket means 20 also comprises, on that wall 12 opposite the wall 12a comprising the slot 13, a substantially vertical appendix 24 which adheres to said wall 12 and projects downwards below the lip 21 so that the front edge 9' of the valving member 9 abuts against said appendix 24 to increase the anti-seepage action. Along its lower surface, the lip 21 can comprise one or more longitudinal recesses 23 (ie extending parallel to the longitudinal extension of the sides of the mouth 8), to define one or more longitudinal ridges 21' to increase the sealing action of the lip 21 against the valving member. In the illustrated embodiment, said recesses 23 are provided along three sides of the mouth 8 but not in that part of the lip positioned along that wall 12 opposite the wall 12a. When in its rest state (ie not in contact with the valving member 9), the lip 21 projects downwards slightly beyond the ideal plane in which the upper surface of the valving member 9 moves. Consequently, when the valving member 9 is inserted into the mouth 8 into contact with the lip 21, this is urged upwards and by reaction presses against the valving member 9 with a certain preload. Consequently because of its action against the surface of the valving member 9, the lip 21 very effectively stops any seepage when the valving member 9 closes the mouth 8. This action is increased by the fact that the material in powder or small-piece form lying above the valving member 9 presses against the lip 21 to further urge it against the valving member 9. Hence an extremely effective seal is achieved for the mouth 8. A rectilinear gasket 26 is also provided, fixed to the wall 12a below the valving member 9 and extending along the slot 13. The gasket 26 has an upper lip in contact with the upper surface of the valving member 9. The gasket 26 is also arranged to scrape the lower surface of the valving member 9 when this is pulled rearwards from the mouth 8. Consequently by virtue of the combination of the gasket 26 and the gasket means 20, any seepage through the slot 13 is prevented, both when the valving member 9 is at rest in its opening or closure position, and while it is being pulled rearwards. The upper surface of the valving member 9 can be of elastomeric material, said elastomer having a greater hardness than the elastomer of the gasket means 20. In this manner a surface can be obtained having excellent abrasion resistance while being sufficiently slidable when in contact with the lip 21. Advantageously, the gasket means 20 can be formed by moulding the elastomeric material in the fluid state onto the frame 10. Both good adhesion to the frame 10 and high constructional accuracy are achieved. For ease of description, the valve of the invention has been described and claimed with reference to the most usual spatial arrangement, ie that in which the valving member 9 lies horizontally and the material to be intercepted lies above the valve. The valve can however be of a different spatial arrangement, for example it can be variously rotated from the illustrated position. The embodiments shown in Figures 4, 5 and 6 differ from that heretofore illustrated in that the plan shape of the passage mouth 8 and valving member 9 are different from that illustrated heretofore. In Figure 4, the mouth 8 has a usual circular shape and the valving member 9 has a known rectangular plan shape with its front portion in the form of a semicircle. The embodiment shown in Figure 5 is new in that the mouth 8 has a convex arched side 8a opposite the side comprising the passage slot. The front side of the valving member 9 is of concave arched shape. This embodiment facilitates the descent of the material, particularly when the valve is close to closure, by preventing "bridges" and other obstructions which easily occur when the material passes through a long narrow slot. Figure 6 is a section showing the shape assumed in this type of valve by the gasket means 20 according to the invention, positioned on the side 8a. In a further embodiment, shown in Figure 7, the frame 10 lies in a substantially horizontal plane, whereas the valving member 9 slides in a plane inclined to the horizontal, the inclination being directed downwards towards that wall 12 opposite the wall 12a (comprising the slot 13). The lip 21 has its upper surface 21' inclined downwards towards the centre of the passage mouth 8. The inclination of the valving member 9 together with that of the surface 21' facilitate descent of the material when the valving member is semi-closed, and in particular when close to closure. This embodiment can be applied to any of the valve types shown in Figures 1, 4 and 5. Numerous modifications of a practical and applicational nature can be made to the invention, but without leaving the scope of the inventive idea as hereinafter claimed.

Claims: A slide valve for material in powder or small-piece form, comprising, in combination: a rigid frame (10) with vertical walls (12) defining a passage mouth (8) for the material, having two straight lateral walls (12) parallel one to the other; a flat horizontal plate (9), defining a valving member to close the passage mouth, horizontally movable through a slot (13) provided in a wall (12a), sliding along said lateral walls (12), the width of the plate (9) being equal to the distance between the lateral walls (12), during said movement the plate being guided by idle wheels (6) pivotably fixed to the lateral walls (12), each idle wheel (6) being rotatable around its axis, the idle wheels (6) acting against the lower edge surface of the plate (9); an elastomeric material gasket means (20) in the form of a closed ring fixed to the frame (10) and extending along the upper peripheral edge of the passage mouth (8), said gasket means comprising, when viewed in section, a lip (21) which projects downwards towards the interior of the mouth (8) in contact with the upper surface of the plate (9), the outer surface of the lip (21) converging downwardly toward the center of the passage mouth, over the upper edge surface of the plate (9), in a closure position the plate (9) being inserted into the mouth (8) into contact with the lip (21) and this being urged upwards and by reaction pressing against the plate (9) with a certain preload; characterised in that : the whole lip (21), in its rest state, projects downwards slightly beyond an ideal plane in which the upper surface of the plate (9) moves; in said closure position, the plate (9) is supported by at least the farthest said idle wheels (6) from the wall (12a) carrying said slot (13) and its upper surface is located in the same ideal plane in which the upper surface moves. A valve as claimed in claim 1, characterised in that said lip (21) comprises along its lower surface one or more longitudinal recesses (23) to increase the sealing action of the lip (21). A valve as claimed in claim 1, characterised by comprising a gasket (26) fixed to a wall (12a) of the frame (10) below the valving member (9) and extending along the slot (13) traversed by this latter, said gasket (26) having an upper lip in contact with the lower surface of the valving member (9) and arranged to scrape said lower surface when the valving member (9) is retracted outwards from the mouth (8). A valve as claimed in claim 1, characterised in that said gasket means (20) comprises a horizontal flat rim (22) fixed to a corresponding upper horizontal rim (14) provided in the frame (10), the lip (21) being joined to said flat rim (22). A valve as claimed in claim 1, characterised in that the upper surface of the valving member (9) is of elastomeric material of greater hardness than the gasket means (20). A valve as claimed in claim 1, characterised in that said gasket means (20) is formed by direct moulding onto the rigid frame (10). A valve as claimed in claim 1, characterised in that said gasket means (20) comprises, on that wall (12) opposite the wall (12a) carrying said slot (13), a substantially vertical appendix (24) which adheres to said wall (12) and projects downwards below the lip (21), the front edge (9') of the valving member (9) abutting against said appendix (24). A valve as claimed in claim 1 where said frame (10) lies substantially horizontally, characterised in that the valving member (9) lies and slides in a plane inclined downwards from the horizontal towards that wall (12) opposite the wall (12a) carrying said slot (13), the lip (21) of the gasket means (20) having an upper surface (21') inclined downwards towards the centre of the passage mouth (8). A valve as claimed in claim 1, characterised in that in plan view the passage mouth (8) comprises a convex arched side (8a) opposite that side comprising the passage slot (13), the valving member (9) having in plan view a front side (9a) of convex arched shape.

Inventors: MARCHESINI VAINER, MARCHESINI, VAINER
Applicants: WAM SPA, WAM S.P.A.
Application year: 1994
Main classification: B65D90
IPC codes: F16K3, B65D90